APPLICATIONS VAV COOLING VAV COOLING & HEATING ADVANTAGES INDIVIDUAL CONTROL REVERSING CHANGE-OVER OPTION EASY INSTALLATION ACCURATE CONTROL NO REGULAR MAINTENANCE LOW OPERATING COST

The slim and attractive shape of the diffuser extrusions ensures that the unit blends into any ceiling design and meets most architectural requirements. At the same time the superior aerodynamic design ensures that air diffusion is draftless, quiet and efficient. The units air pattern is adjustable by adjusting the air pattern controllers from below. Adjustment allows the air to blow in four possible patterns, opposed horizontal blow, one way horizontal blow in either direction and vertical downward blow.


2 OPERATION

GENERAL DESCRIPTION

Room temperature is controlled by varying the supply air volume in accordance with demand. Volume control is achieved by opening or closing a set of aerodynamically designed, extruded aluminum vanes by means of a thermal actuator, so as to vary the aperture through which the air passes. This results in the VARIABLE GEOMETRY concept, which effectively maintains air discharge velocities throughout the range of volume control, from 100% down to approximately 30%.

The thermal actuator is driven by means of a wax filled thermal element which responds to changes in sensed temperature. The wax contained in the thermal element expands and contracts at the formulated temperatures. With a rise in sensed temperature the expanding wax extends the plunger, causing the amplifying mechanism to move the vanes so that the supply air volume is changed to the extent that is required to maintain a constant room temperature. When the wax cools, the plunger retracts under the action of the return spring, causing the vanes to move in the opposite direction to counter the change in the sensed temperature.

* This product is protected by US Patents: 5,647,532; 6,254,010 B1; 6,702,187 B2, Australian Patents: 700908; 755770 and South African Patents: 96/4791; 2000/1891; 2002/8924. Patents are pending in the USA and other countries.

The standard VLN4/5 diffusers are available in four sizes, 600mm (24 in.), 900mm (36 in.), 1200mm (48 in.) and 1500mm (60 in.). The VLN diffuser section has two slots and is available in a range of standard sizes to suit typical applications. Special lengths are available on request. The extrusions have been designed for butting together dummy or active lengths accurately so that an unlimited length of continuous diffuser is possible without sacrificing its attractive appearance. In this case the volume control modules may be placed anywhere along the length of the continuous diffuser.

The volume control section is constructed using corrosion resistant pre-galvanized sheet steel. The extruded aluminum diffuser sections are finished in epoxy powder coated textured white or natural anodized aluminum.

VLN4 HEATING/COOLING VARIABLE VOLUME LINEAR DIFFUSER

The VLN4 heating/cooling diffuser incorporates a change-over thermal element which automatically changes the action of the diffuser when in the heating mode. This allows full VAV control of room temperature when warm air is supplied to the diffuser.

Change-over between heating and cooling modes occurs in the temperature range (20°-28°C) 66 - 84°F. For satisfactory temperature control, the duct temperature should be maintained below (20°C) 66°F or above (28°C) 84°F.

In cooling mode decreasing room temperature will result in increased diffuser flow. In heating mode decreasing room temperature will result in decreased diffuser flow.

VLN5 COOLING ONLY VARIABLE VOLUME LINEAR DIFFUSER

The VLN5 Cooling Only diffuser does not incorporate a change over thermal element, making it suitable for systems having cold supply air only.

TEMPERATURE ADJUSTMENT

The room temperature sensing element is located above an access panel induction plate. Adjustment of the room temperature setpoint is achieved by rotating the aluminum pill cap as indicated inside the thermal actuator housing. It is advisable that no changes are made to the factory setpoint of (22°C) 72°F until the space is occupied. This will give realistic operating conditions, after which individual units may be adjusted to suit individual requirements.

AIRFLOW DIRECTION

A user friendly feature of the RICKARD VLN4/5 is the ease with which the direction of the airflow may be changed. Although the airflow direction is not normally changed once the system is operating, it does simplify the ordering and installation procedure. The choice of one-way horizontal blow to either side or opposed horizontal blow is easily implemented on site by simply flipping the pattern controllers in the appropriate direction. For abnormally high ceilings it is possible to direct the air downwards for better room penetration.

MAINTENANCE

As with all RICKARD AIR DIFFUSION products, the VLN requires no regular preventative maintenance.

3 DIFFUSER SELECTION

GENERAL

The first consideration when designing a system is to calculate the required air volume and temperature to satisfy room conditions at maximum heat loads. It is recommended that ducting is sized using the static regain method. Velocities in the branch ducts should be in the range (3.5m/s – 6m/s) 700-1200ft/min. Thereafter the following should be considered.

THROW

This is the distance from the diffuser at which the velocity has reduced to (0.25m/s) 50 ft/min when measured (25mm) 1 in. below the ceiling (or from the wall) with the diffuser in the fully open position.

NOISE LEVEL

The NC levels given in the selection table apply to a single diffuser mounted in the ceiling of a room having a Sound Absorption of 10db in Octave Bands having centre frequencies from 125 to 8000hz. i.e. the difference between the Sound Pressure Level (dB re: 10-6 Pa) and Sound Power Level (dB re: 10-12W) is equal to 10dB. These represent only the noise regenerated by the diffuser and do not take into account any duct-borne noise.

DUCT STATIC PRESSURE

Diffuser performance has been established using diffuser neck TOTAL PRESSURE, although what is normally known and controlled is duct STATIC PRESSURE. What happens between the duct and the diffuser depends on the length and type of flexible duct. For simplicity, it can be assumed that the duct STATIC PRESSURE approximates diffuser neck total pressure. This is a valid approximation for systems where flexible duct lengths are not excessive as the loss due to friction in the flexible duct (+/-10Pa.) would normally be approximately the same as the velocity in the diffuser neck.

NOTE: Avoid placing restrictions (such as manually operated dampers or squashed flexible ducts) at any point in the branch ducts. The reason for this being that at maximum flow these restrictions will result in significant static pressure loss, but at minimum flow conditions will offer virtually no resistance, which will result in the static pressure at the diffuser being too high.




· Throw values apply to a terminal velocity of 50fpm, measured under isothermal conditions.
· Volume flows are the quantity of air that flows into the conditioned spaces. Additional air (induction air) is required to induce room air over the actuator. This induction air is discharged into the ceiling space. Induction air flows are given in the table below and must be added to the volume flow from the tables above to obtain the total flow required by the diffuser.

· Throw values apply to a terminal velocity of 0.25m/s, measured under isothermal conditions.
· Volume flows are the quantity of air that flows into the conditioned spaces. Additional air (induction air) is required to induce room air over the actuator. This induction air is discharged into the ceiling space. Induction air flows are given in the table below and must be added to the volume flow from the tables above to obtain the total flow required by the diffuser.



4 DIMENSION DATA





5 ADVANTAGES OF THE THERMAL VLN

PERSONALIZED COMFORT

The VLN4/5 controls it’s own VAV zone, with each diffuser adjusting between (20°-24°C) 66 - 77°F. The VLN4/5 will sense and control the temperature within (1.5°C) 3°F of setpoint. (Factory setting (22°C) 72°F). There is no need for thermostats, which are often situated incorrectly. This is because it is situated in the diffuser itself.

CAPITAL & OPERATING COST SAVINGS

The VLN4/5 is a self powered system, which requires no outside power source i.e. electrical or pneumatic. There are numerous savings on cabling/piping, thermostats and other electrical/mechanical equipment.

LOW MAINTENANCE

The VLN4/5 is reliable and requires no regular maintenance. The absence of electrical or pneumatic equipment and accessories also means less maintenance and fewer potential problems. The only parts ever likely to need attention are the thermal elements and these can be easily replaced.

FLEXIBILITY

The VLN4/5 can easily be relocated, there is no need to move electrical cables, pneumatic tubes or other related equipment. If additional units are required, their addition does not disrupt the rest of the air handling system.

TEN YEAR WARRANTY

RICKARD AIR DIFFUSION (Pty) Ltd (RICKARD) warrants that its Thermal VLN Diffusers, exclusive of any options or accessories not approved by RICKARD (whether factory or field installed) shall be free from defects in material or workmanship for a period of ten (10) years from the date of shipment and agrees to repair or replace, at its option, any parts that fail during said period due to any such defects which would not have occurred had reasonable care been taken, provided that such parts have been inspected by RICKARD and found defective and provided the diffusers have been given normal and proper usage and all parts and controls remain unaltered.

RICKARD makes no warranty of merchantability of products or of their fitness for any purpose or any other express or implied warranty which extends beyond the limited warranty above. RICKARD’S liability for any and all losses and damages resulting from defects shall in no event exceed the cost of repair or replacement of parts found defective upon examination by RICKARD. In no event shall RICKARD be liable for incidental, indirect or consequential damages or damages or injury to persons or property. RICKARD shall not be responsible for freight to or from its premises in connection with the inspection, repair or replacement of parts under the terms of this limited warranty, nor for the cost of removal or installation.

Rickard Air Diffusion (Pty) Ltd. reserves the right to change specifications and data without prior notice.

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